Kidnappers abducted 42 people, including 27 students, three teachers and relatives of school staff.
Nigerian security forces are tracking the armed gang that kidnapped more than 40 people from a school on Wednesday after President Muhammadu Buhari ordered a rescue operation.
The abduction in Kagara in central Niger State on Wednesday was the latest mass kidnapping in the country where criminal gangs, known as “bandits”, have stepped up attacks.
Heavily armed men in military uniforms raided the Government Science College in Kagara, killing one student and spiriting others into a nearby forest.
Kidnappers abducted 42 people, including 27 students, three teachers and relatives of school staff, according to Niger State officials.
“We are doing whatever we can to free the students and the teachers,” Niger State information commissioner Muhammad Sani Idris told AFP news agency.
“They are being pressed. We have security agents on their heels. We are hoping we will rescue the students in a very short time.”
Kidnappers have made no ransom request and authorities would not pay any, he said.
The Kagara school was closed up on Thursday and the town was quiet, an AFP journalist at the scene said.
In a separate incident, armed men attacked Gurmana, another town in Niger State, on Wednesday night, killing two people and abducting several others, said Ibrahim Audu Hussein, the spokesman for Niger’s emergency management agency.
Al Jazeera’s Ahmed Idris, reporting from the capital Abuja, said kidnapping for ransom has now become a big business in Nigeria.
“From the north down to the country’s south, hundreds of Nigerians are abducted every week for ransom,” he said.
“Despite military offensives, the problem continues to grow. Although there are no official statistics, it is estimated $20m was paid in ransom money to kidnappers last year in a country – Africa’s largest economy – where poverty is on the rise.”
The latest mass abduction came just two months after 300 students were kidnapped from a school in Kankara in nearby Katsina, Buhari’s home state, while the president was visiting the region.
The boys were later released after negotiations with government officials, but the incident triggered outrage and memories of the kidnappings of Nigerian schoolgirls by armed fighters in Dapchi and Chibok that shocked the world.
Out of the some 270 girls who were kidnapped by the Boko Haram group from Chibok, at least 100 are still unaccounted for.